Computer system and EMI structure thereof

ABSTRACT

A computer system and the EMI prevention structure thereof, comprising: a housing for covering the computer having a leading groove formed inward thereof, a main board having a ground layer formed in the periphery thereof wherein the width of the main board is substantially equal to the interval of the leading groove and a shielding device comprising a pair of substantially parallel metal plates and a metal side plate to form a cuboid with an opining so that said shielding device can be connected the ground layer, wherein at least one spring piece is installed on the plate.

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] The invention relates to an electromagnetic interference (EMI) prevention structure, and more particularly to an electromagnetic interference prevention structure for a person computer.

[0003] (2) Description of the Prior Art

[0004] Some many electric products, especially information products such as a person computer or a set top box, comprise metal housings for covering a main board of a computer system, so as to protect the electric components therein and to reduce EMI for the electric components. It is been proven that stronger EMI generated by the electric product causes more harm of a human, especially for the high working frequency of the electric product. Therefore, a specified security standard to limit the level of EMI from many kinds of the electric product is applied in many countries.

[0005] In a conventional technique, the main board in the metal housing is usually fixed into the inner side of the metal housing by screws so as to reduce the potential between the ground voltage of the main board and voltage of the metal housing. Thus, the EMI generated from the potential can be reduced. Additionally, the conductive surface can be extended because of the contact between the main board and the metal housing so that the energy of the EMI may weaken.

[0006]FIG. 1 shows a main board of a computer system in conventional technique, wherein the upper cover of the housing is removed such that it is clearly disclosed the relation between the main board and the metal housing. A computer system 10 comprises a main board 11 and a metal housing 13 for covering the main board 11. A plurality of through hoes 15 are formed on the main board 11 so that the main board 11 is secured in one surface of the mental housing 13 by screws 12. The lower portion of the screw 12 is tinned and is connected with a ground layer 14 of the main board 11 so as to reduce the potential between the voltage of the main board 11 and voltage of the metal housing 13. Thus, the EMI generated from the potential can be reduced. Additionally, the conductive surface can be extended because of the contact between the main board 11 and the metal housing 13 so that the energy of the EMI may be weakened.

[0007] However, the assembly for securing the screws 12 and the mental housing 13 is difficult. Moreover, the gap between the metal housing 13 and the main board 11 will increase because the main board 11 is merely secured by screws 12, so that electromagnetic wave may easily pass through the gap.

SUMMARY OF THE INVENTION

[0008] Accordingly, it is a primary object of the present invention to provide a computer system and an EMI preventing structure thereof

[0009] To achieve the above objects, the receiving device in accordance with the present invention comprises the storage element and the cabinet.

[0010] All these objects are achieved by the EMI preventing structure described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which

[0012]FIG. 1 is a perspective view of a main board and a metal housing in accordance with the conventional technology, showing the connection status wherein a upper cover of the metal housing is removed;

[0013]FIG. 2 is a perspective view of a preferred embodiment of a main board, shielding devices and a metal housing in accordance with the present invention, showing the connection status wherein a upper cover of the metal housing is removed; and

[0014]FIG. 3 is a detail view of the preferred embodiment of the shielding device, wherein FIG. 3(A) is a front view thereof, FIG. 3(B) is a rear view thereof and FIG. 3(C) is side view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] The invention disclosed herein is directed to a shielding device. In the following description, numerous details are set forth in order to provide a thorough understanding of the present invention. It will be appreciated by one skilled in the art that variations of these specific details are possible while still achieving the results of the present invention. In other instance, well-known components are not described in detail in order not to unnecessarily obscure the present invention.

[0016] Referring now to FIG. 2, a preferred embodiment of the present invention is shown perspective, in which a perspective view of a preferred embodiment of a main board, shielding devices and a metal housing in accordance with the present invention, shows the connection status wherein a upper cover of the metal housing is removed. The computer system can be a personal computer, a set-top box or a PDA. The computer system comprises: a main board 22, a plurality of shielding devices 23 which is embedded with the periphery of the main board 22 and a metal housing 20 for covering the main board 22. The metal housing 20 is pressed from a metal plate and is formed a substantial cuboid wherein a leading groove 21 is installed on each opposite surface. The leading groove 21 has a pair of parallel ribs 211 and the interval of the ribs 211 is similar to the width of the main board 22 so that the main board 22 can be embedded in the leading groove 21 to provide a simple assembly for the computer system. In order to reinforce the connection between the main board 22 and the leading groove 21, the elastic shielding devices 23 are installed in the opposite sides of the main board 22 before the main board 22 is inserted into the leading groove 21. Thus, when the main board 22 with the shielding 23 is inserted into the leading groove 21, the shielding devices 23 are interfering with the ribs 211 due to the width of the main board 22 with the shielding 23 is slightly larger than the interval of the ribs 211 such that the main board 22 can be stably installed within the metal housing 20.

[0017] Further referring to FIG. 2, the main board 22 is general a print circuit board having several electrical components and connectors installed thereon so as to achieve the specific function. As this is prior art, the detailed statements for the above will be not described in the following specification. It is noted that the opposite peripheral sides of the main board 22 are tinned and are formed ground layers 211. the ground layer 211 is electrically connected with the shielding device 23 so as to make the ground voltage of the main board 22 is equal to the voltage of the metal housing 20. Furthermore, a plurality of through holes 222 are formed on the ground layer 211 such that the shielding devices 24 can be fixed on these through holes 222.

[0018] Please refer to FIG. 3 which is a detail view of the preferred embodiment of the shielding device, wherein FIG. 3(A) is a front view thereof, FIG. 3(B) is a rear view thereof and FIG. 3(C) is side view thereof. The shielding device 23 comprises a pair of substantially parallel metal plates 230 and a metal side plate 231 to form a cuboid with an opining. The shielding device 23 is pressed from a more conductive metal such as a copper plate or an aluminum plate. The metal plates 230 or the metal side plate 231 comprise a plurality of spring pieces 232. In the preferred embodiment, a spring latch 233 is formed on the metal plate 230. As shown in figures, when the spring pieces 232 and spring latch 233 are manufactured, the sharp of the same can be directly pressed and formed by the model. Further referring FIG. 3(C), the spring piece 232 is protruded and is directed outward the metal plate 230 or the metal side plate 231 so that the width of the shielding device 23 is slightly larger than the interval of the leading groove 21. On the other hand, the spring latch 233 is directed inward the metal plate 230, thereby the spring latch 233 of the shielding device 23 can be embedded within the through hole 222 of the main board 22.

[0019] When installing the main board 22, the opening of the shielding device 23 is aligned with and pushed into the ground layer 221 in the edge of the main board 22. As shown in FIG. 3(C), because the spring latch 233 is directed inward the metal plate 230 so as to form a barb, the spring latch 233 can be embedded within the through hole 222 of the main board 22 thereby the shielding device 23 is stably fixed in the main board 22. When the main board 22 with the shielding devices 23 is inserted into the leading groove 21, the spring pieces 232 is compressed by the leading groove 21 and than the main board 22 is retained within the leading groove 21. Therefore, the electrical connection between main board 22 and the metal housing 20 can be maintained even if the computer is shocked such that the EMI can be presented. Furthermore, the present invention can simplified the assembly because the main board 22 can be directly pushed into the leading groove 21.

[0020] While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be without departing from the spirit and scope of the present invention. For instance, the spring latch 233 can be formed on the metal plate 230. 

What is claimed is:
 1. A computer system and the EMI prevention structure thereof, comprising: a housing for covering the computer having a leading groove formed inward thereof; a main board having a ground layer formed in the periphery thereof wherein the width of the main board is substantially equal to the interval of the leading groove; and, a shielding device comprising a pair of substantially parallel metal plates and a metal side plate to form a cuboid with an opining so that said shielding device can be connected the ground layer, wherein at least one spring piece is installed on the plate.
 2. The computer system and the EMI presentation structure thereof according to claim 1, wherein said shielding device is pressed from a metal plate.
 3. The computer system and the EMI presentation structure thereof according to claim 1, wherein the ground layer is a tinned layer formed on the main board.
 4. The computer system and the EMI presentation structure thereof according to claim 1, wherein the spring piece is integrally formed with said shielding device.
 5. The computer system and the EMI presentation structure thereof according to claim 1, wherein the main board further comprises a plurality of through holes formed on the ground layer.
 6. The computer system and the EMI presentation structure thereof according to claim 5, wherein a plurality of spring latches with respect to the through holes are installed on said shielding device.
 7. The computer system and the EMI presentation structure thereof according to claim 1, wherein the spring latches are integrally formed with said shielding device.
 8. A metal shielding device which is embedded on a main board for preventing EMI, comprising: a pair of substantially parallel metal plates connected with a metal side plate to form a cuboid with an opining so that said shielding device can be connected the ground layer, wherein at least one spring piece is installed on the plate.
 9. The metal shielding device according to claim 8, wherein the spring piece is integrally formed with said shielding device.
 10. The metal shielding device according to claim 8, wherein the main board comprises a ground layer for electrically with said metal shielding device. 